(a rough voice but can also be nice, for reference go to the dub episodes) 

(from wiki)

He transforms into an orange cat whenever he is hugged by a person of the opposite gender or when his body comes under a great deal of stress. This animal is not in the Chinese zodiac, but legend says would have been if it had not been tricked by the Rat into missing the induction feast.  Also, this could be and probably is why he and Yuki do not get along very well. As part of his curse, Kyo transforms into a "monster", whenever his Juzu beads bracelet are taken off.

Kyo is usually short-tempered, impulsive, and rude, but that is only one side to this complex character. He doesn't like to show his feelings and is very protective of those he cares for.  He also appears to have a strong dislike for leeks.

Kyo's mother committed suicide by walking in front of an oncoming train when he was a young child of possibly four to six years old.  His father later abandoned him. Kazuma Sohma, whose grandfather was the previous cat, decided to take Kyo in as his own son and the two form a relationship that seems blood-related. People have criticized Kyo throughout his life for his differences, too frightened or never bothering to glance beyond the label of "The Cat" and regard Kyo as a true person. Like most of the Sohmas, throughout his school years, he begins to get picked on for the color of his hair.

His bracelet of beads was made from the bones of a priest and warrior, and so they are a powerful protective charm.  Whenever these beads are taken off his wrist, Kyo transforms into the cat's "true form", and only the cat transforms into this form. The Juzu beads are handed down to the current cat of the Zodiac from the previous cat, and must always be worn.  

He also made a bet with Akito that he will beat Yuki before they graduate. But if Kyo doesn't beat Yuki before they graduate, Kyo will be locked in the Cat's Room for the rest of his life; if he does, then he will be accepted as a full member of the zodiac.